1. Field of the Invention
This invention relates to a side knock-type writing instrument, e.g., a mechanical pencil or a ball-point pen, and more particularly to a side knock-type writing instrument provided with a finger gripping member for ensuring a user's comfortable gripping of a barrel of the writing instrument so as not to cause a user to be fatigued in use of the writing instrument.
2. Description of the Prior Art
This kind of side knock-type ball-point pen is disclosed in Japanese Utility Model Publication No. 19835/1995. Referring now to FIG. 1, the conventional ball-point pen comprises a barrel 1, a refill 3 axially movably disposed within the barrel 1, a first spring member 5 for urging the refill 3 into a retracted position, an actuating member 7 for- causing the refill 3 to be moved an extended position, a rotary cam mechanism 9 disposed within the barrel 1 and placed behind the refill 3, and a second spring member 11 having a resilience weaker than that of the first spring member 5. The barrel 1 has a head section 13 threadedly attached to a front end thereof, and an axially extending hole 15 formed in a potion of a wall of the barrel 1 which is adjacent the front end of the barrel 1. The refill 3 is provided with a spring clip 17. The first spring member 5 is disposed between the head section 13 of the barrel 1 and the spring clip 17. The actuating member 7 is axially movably received in the axially extending hole 15 and engaged with the refill 3. The rotary cam mechanism 9 includes a cam body 19 disposed within the barrel 1 so as to surround a rear end portion of the refill 3, a rotary element 21 mounted on the rear end portion of the refill 3 and disposed within the can body 19, and a cam bar 23 received in the cam body 19. The cam bar 23 has a first end portion and a second end portion. The first end portion of the cam bar 23 is engaged with the rotary element 21. The second end portion of the cam bar 23 extends in a rearward direction through a rear end of the cam body 19. The second spring member 11 is disposed between a stopper member 25 fitted in a rear end of the barrel 1 and the cam bar 23, whereby the cam bar 23 is always urged forward.
Indeed the prior art referred to in the above is effective in selectively retracting and extending a writing tip of the refill 3 by causing the actuating member 7 to be axially moved along the axially extending hole 15 of the barrel 1.
However, the conventional writing instrument is not provided with any finger gripping member, so that it will cause a user to be fatigued during prolonged writing by the writing instrument and it will be liable to slip off the user's fingers during the writing.
There is not yet proposed a side knock-type writing instrument which is provided with a finger gripping member. When a side knock-type writing instrument is provided with any finger gripping member, it is necessary to cause the finger gripping member to be attached to a barrel of the writing instrument such that movement of the finger gripping member relative to the barrel is prevented.